Multiple-station telephone system.



PATENTED JULY 23. 1907.

A. J. FARMEE. MULTI PLE STATION TELEPHONE SYSTEM.

APPLICATION FILED PEB.4. 1902.

' s SHEETS-SHEET 1.

PATENTED JULY 23, 1907.

APPLIOATION FILED PERM 1902.

3 SHEETS-SHEET 2.

WITNESSES.

No. 860,860. 'PATENTED JULY 23, 1907; A. J. FARMER.

MULTIPLE STATION TELEPHONE SYSTEM.

APPLICATION FILED 11:12.4. 1902.

' s SHEETS-SHEET a.

.J' *1 BIL sll ll1l" WITNESSES. v INVENTOR.

MW wfixflm ARTH R J. FARMER, or DETROIT, MICHIGAN.-

MULTIPLE-STATION TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented July 23, 1907.

Application filed February 4=.1902. Saris-1N0. 92,567.

To all whom it may concern:-

Be it known thatI, ARTH R J. FARMER, a citizen of the United States ofAmerica,-and a resident of Detroit, in the county of Wayne and State ofMichigan, have invented certain new and useful Improvements in.

Multiple-Station Telephone Systems, of which the following is aspecification.

-My invention relates to improvements in multiple station, or party linetelephone system, and has for its object the provision of apparatusembodying selective, secrecy, and busy signal features, and forsimplifying the work of the operator at the central ofiice.

v It has been my design to depart from the standard exchange circuitsand apparatus only in simple and necessary particulars, thus enabling meto use the invention in systems already installed.

The selective feature of my system, I obtain by interposing between thecentral ofiEice and the several parties served by a given line, ajunction-box containing switching mechanism for alternatively connectingin circuit all of the parties'upon the line, or

merely the single party called or calling forconnection. The actuationand restoration of the junctionbox apparatus are controlled by'theexchange operator through a key connected with the operating battery;

inwhich operations she is guided by means of a supervisory lamp orsignal.

In selectingm. party, current is transmitted to the junction-box over.both sides of the. 'line to ground; while. for "effecting itsrestoration, but one side is used,

the apparatus automatically stopping in its normal position for calling,or receivinga call from any of the parties; Each party is informed ofthe condition of his line by means of an automatic busy signal.

7 The invention will be more readily understood by apparatus, andatelephone system embodying my improvements.

Figure l thereof shows in levation, the junctionbox apparatris forswitching thevarious subscribers or parties into and out of circuit;Fig. 2 is a detail, showing the preferred form of switching contactsFig.

3 is a diagram of the junction-box and subscribers circuits showing oneparty line station in some-detail,

and, Fig. 4 diagrammatically illustrates the central oflice apparatus.

The same character of reference isemployed through? out the drawings toindicate similar parts. 1

Referring first to Fig. 1; it will be seen that the prin- Y cipalfeature of the junction-box switching apparatus is a spider s rotatablymounted upon a shaft a which.

bears a ratchet-wheel w controlled by electrosmagnct m. Theratchet-wheel is engaged and operated by a pawlp carried'by the armatureof the electro-magnet.

The radial limbs of the spider bear variously positioned engaging shoesa a-b, bc, d, e, adapted, during the rotation of the spider, to closethe contactsa, b b, also contacts l11 corresponding to and connectedwith the .party line stations of similar number indicated at the left ofFig. 3. The shoes for closing station contacts are so positioned thatnotwo of the latter canbe closed at the same timey'i. e. during any oneposition of the spider. By observing the concentric dotted circles insaid figure, it will be at once apparent which contacts are actuated byany given shoe. The actuating electro-magnetic apparatus is of thevibrating type, so that the operator may, by depressing a key S, throwcurrent from batteryB to line, and step around the spider to theposition necessary for connecting in circuit the desired subscriber.

In Fig. 3 the spider and acutating mechanism are shown in normalposition below or vertically displaced from the several junction-boxcontacts, circularly arranged near the upper part of the diagram. Thecontact b is then closed by the engaging shoe b which insures thecompletion of the circuitfrom the exchange to all the stations 1-11 whenthe line is not in use. Immediately spider sisrotated out of its initialposition, however, contact is broken at W, disconnecting all thestations from circuit until some one of the contacts 1-1.1

' has been closed by the shoes 0, d, or 0. This will serve to connectthe corresponding station to line, through conductors. In its initialposition, also, the spider maintains open the contacts band b andaccordingly, to complete circuit through wire 15 to magnet m, it isnecessary to energizerelay y; thus closing a shunt about contact 1).Relay 3; is bridged between line and ground; the continuity of thecircuit being controlled at contact f,.which will be closed immediately'relay 2 is energized. In order to rotate the spider from its initialposition, accordingly, it is necessary to send current over line wires 12 in parallel; but immediately this occurs, contact I) is closed and theHow of current over line wire 1 alone is required to continue therotation of the spider, and restore it to its initial position;

when it will be automatically stopped by the re-openiug of the circuitto magnet on at b. The energization of relay 2 closes the contacts at f,forming a part of a bridge betweenthe line conductors, which is in turncontrolled by contact a. This bridge is between the exchange and thebreaks'in the line conductors. Whenever one of the party-line contacts1, 2, 3, etc. is closed, contact a is simultaneously closed by one ofthe shoes '01, a etc; hence, while current is being sent over line wireI, the supervisory lamp at the central station will be extinguished eachtime a station is con nected in circuit, by reason of the closureof'this lowresistance bridge; therefore the operator presses her signalsmay, of course, be substituted for said lamps, if desired. 70, k aremultiple-contact restoring re-- selecting key S until the supervisorylamp has flashed the requircdunnnber of times; releasing the same afterthe hash occurs corresponding in number to that of the station desired.In order to automatically stop the spider when selecting a callingstation, additional contact'sand relay x are provided. To secure thisresult the relay is so placed that it will be switched into the circuitwith the main line wire 2 by means of contact h when selecting-currentis sent over line wire 1. The current over the former passes to groundvia contact f and relay y there being no path from 2 to ground fordirect current beyond this point, while the bridge between wires 1 f and2", which is closed by shoes il a at a, is on the exchange side of relayx. Accordingly said relay, when thus in circuit, is energized only bycurrent traversing the complete metallic circuit which will not occuruntil the spider has completed circuit to the calling station. Thecurrent then which ordinarily controls the supervisory signal relay atthe exchange, will also pass through relay :0, energize the same, andcause the circuit to be broken at i. This will serve to cut out magnet mand prevent further rotation of the spider; The -operating battery thenbeing disconnected from line, the armature of relay 2 is restored and ashunt around relay .1: is closed at g. Whenone of the 'party linesubscribers desires a connection, selects ing current is sent to lineand relay :0 would be immediately cut in, thus disconnecting magnet m,were it not for the fact that shoe b iu'its initial position separatescontacts I) which control the circuit through relay :12.

In Fig. 4 is shown diagrammatically a typical exchange circuit withauxiliary relays and circuits for use in-operating the party-linejunction-box apparatus. It will be noticed that the continuity of theordinary metallic cord and plug circuit requires merely to be brokenatcertain points for permitting the use of auxiliary keys and relays;provided for special purposes. My description will be directedprincipally toward these alterations,'in order to set forth more clearlymy improvements, since those skilled in the art will at once appreciatethe features -common to other systems. It will he recognized that P isthe calling, and P the answering plug, with which are respectivelyconnected keys R, S, K and K, S, L adapted to control the ringing andlistening circuits, and the several circuits of the operating batteries.In practice said keys will be combined'as suitable selecting andringing, and selecting and listening keys. Bis an auxiliary battery, andZ, Z are the supervisory and auxiliary signal lamps Other suitable laysWhose purpose will later be explained.

-, Recurring briefly to Fig. 3, before proceeding with any furtherexplanation, it will be seen that the s'tation apparatnsof subscriber 11is diagrammatically n sired, may be connected to provide a full metallicringing circuit therefor. The highwound magnet j of the subscribcrsbusy-signal is connected between the other line conductor, or itsextension beyond the-junction-box, and the ground. This signal comprisessimply a rotatable disk 9" provided with alternating sectors of whiteand black, one of which will always be displayed at an opening in thesubscribers instrument box. Each time the magnet j is energized itsarmature j, by means of a pawl engaging the ratchet-wheel associatedwith disk j, advances said wheel and disk one step, thereby indicatingthe condition of the line, a black sector, for example, showing when thepartyline is busy.

After reading the foregoing, a somewhat detailed description of theoperation of my improved system, which I shallnow make, will be readilyunderstood by those conversant with telephone practice. Assuming nowthat the exchange operator finds, upon plugging into the jack of acalling line that station 3-is desired; plug P is inserted in the jackof the party-line and key S is depressed, which serves to connect bat-.

bridge from conductor 1 to ground via wire L, contacts y, 'i and thewindings of actuating magnet 'm.

. Thus excited, said magnet rapidly inakes and breaks the circuitthroughits windings, intermittently attracting its armature and therebystepping around spider s in a clockwise direction; this actioncontinuing as long as pressure is maintained on key S.

As before explained, shoes (1, a 0., etc. will complete circuit throughcontacts a at the same time that shoes 0, d, e successively close thecontacts 1, 2, 3, etc., controlling circuits to the correspondingpartiy-line stations. This closure of contacts a completes each time, alow-resistance bridge between the line conductors by way of contact f,causing the supervisory lamp to be extinguished whenever a station isselectively connected in circuit.

.Underthe conditions assumed, the operator notes that the lamp 1 istwice extinguished, and releases the key the'third time the lamp ceasesto burn. It will be observed that the contact-making shoes of the spiderare made of sufiicient length to permit the operator to release the keybefore the spider can break the "desired connection. Line conductor 2 isnow open at b but a shunt is established for the desired party atcontact 3. Station 3 thus is the only station connected in circuit withthe exchange, said circuit and contact shunting the break therein, theexchange side of the breaks in said conductor 2, thence to the sleeve ofplug P; The operator now rings subscriber 3' by depressing key R, whoupon answcringconnects a low-resistance bridge between conductors 1, 2",thus extinguishing the supervisory lamp and informing the operator thatthe subscriber has respondedr The talking circuit thus established maybe tracedthrough the cord circuit as fo1lows;i;om the calling station tothe sleeve of plug P, key L, key S, wire I), relays r, 1, wire D, key S;key R, sleeve 'of plug P, to the called station, thence to the tip ofsaid plug, as already described, key R, key S. wire C, wires 1', 2, 3contacts s of the uneircited relay in, wires 4, 5, C 6 7, contacts s ofthe unexcited relay Zc, wires 8, 9, 10, C keyS key L, and to the tip ofthe plug P From the above it will be seen that contacts s 1and 3 are theonly points at which 'the eontinu1ty or the circuit can be broken, otherthan those ordinarily tion, and said contacts s", 3 remain closed untilrestoring current is sent to lineupon the conclusion of theconversation.

Upon the subscribers hangin 'up their receivers,

the supervisory lamp is lighted in the well known manner, thus notifyingthe operator to disconnect. Before removingjhe plugs, however, theoperator momentarily presses key K, transmitting current over thefollowing circuitz-from battery B, wire 11,

' relay is, wire 14, key K, wire 15, wire 16, wire 17, supervisory lamp1, thiinble of the party-line jack, relay w, and thence to ground. Therelay k is excited and attracts its armature, closing its-multiplecontacts at.

has been closed, unless key K has, also been closed and a shunt around Shas thus been closed atp; The contact made by 0 closes the circuitincluding battery l3 and the auxiliary supervisory lamp 1, whichpreferably is of different color than lamp 1.

These circuit conditions obtain until the plug P is,

removed from'its jack, when the relay 7c will be restored to its normalposition. The operating battery and resistance R are. of course, soproportioned as to insure the actuation ofthe apparatus seriallyconnected therewith. The current supplied to line conductor flows to thejunction-box and reaches ground by way of a bridge including relay 2,and another including conductor 1!, contacts b and i, and actuatingmagnet m. Although relay z is incidentally energized, no operativefunction is thereby attained, but the "current flowing through magnet mserves to rotate the spider s in continuation of its movement, untilshoe b reaches its normal position to break contact at 6. Since there isno current flowing over line canductor 2 relay 3; remains inert, and thecircuit, to

magnet m is thus automatically'broken, and the spider is stopped in itsinitial position.

During the above recited operation contact a will .be closed and openedat intervals during the rotation 'of the spider, causing the supervisorylamp 1. at the ex-. change alternately to burn and become-exting lisheduntil the spider has reached its normal position,-iwhen said lamp willremain lighted as a signal for the operator to disconnecti The-functionof the auxiliary superand indicate that the line'is free, It will beobserved -that the other, or answering side of the cord circuit,

' use of the line, and the other stations uponsaid line are visory lamp1 is to prevent the disconnectionuoi a party-line nntil the restoringcurrent-has been trans.-

mitted to leave the linein normal condition-for sending and receivingcalls; and accordingly the operator must not take down a party-lineconnection vuntil both the supervisoryand auxiliary lamps are lighted.Upon receiving the subscribers signal to disconnect," the op-- .erator,accordingly, will press key K, accomplishing 1 the above describedresult; meanwhile attending-mo mentarily to her other duties; andwhenthe automatic restoration of the'junction-box apparatus has beeneffected, and both lampsl and l are lighted the opera- "tor takes downthe connection, knowing that the line opened when listening in, calling,or selecting a sta-;

is in normal condition. 1 The current thus transmitted to effect therestoration of the junction-box apparatus, also flows in part throughthe busy signal magnets at the several subscribers stations, therebyadvancing the controlled disks one step to display a white sectorsimilarly is provided with selecting andrestoring keys S, K, and thatthe'multiple-c'ontact restoring relay 7c is present, so thata'party-line subscriber calling for a connection, likewise has,temporarily, the exclusive notified of the condition of the' line'bymeans of their,

busy'signals. All this is accomplished in manner ekactly analogous tothat of selecting a called p'arty,',

with the; exception'that the operator, 'as explained,

:does not have to watch the number of'flashes, but de- Lpends on therelay :0 and thejunction-box' apparatusto automatically selectthecalling station, and the res-" :toration of the .junction-box'apparatusis similarly brought about; Therefore,' I it will -be unnecessary torefer in further detail to these operations.

It willbe appreciated that,-as nearly as possible, I

" have rendered automatic the selective, restoring and- A busysignal-features of my system,'. in order to relieve the operator ofextra labor and also insure greater accuracy. In the systemasthu'srequipped, a corn'paraof course, be' disposed in the system to suitlocal concli- 115 tions. Preferably it issituated as centrally aspossible with respect to-the group of parties served; thereby reducingthe length of extension line conductors required. Thus it maybei'nstalledlat some one of the party-line stations,.if desired, or itmaybe equipped with'a'weather-proof housing or casing,:-an d be-placedupon a convenient pole. Suitable terminals for connecting up theentering lines, naturally will be mounted thereini Containing, asitdoes, all the' additional actuating apparatus Quts'id'eof theexchange;and this being of an extremely simplecharactei, the junctionbox isatflolicemonvenientior testing and repairing.

- Modificationsto suit arisingconditions will suggest themselves tothose skilled in the art, and I do not desireto be understood as sttingforth herein, more than illustrative apparatus and circuit arrangementsembodying my invention; and accordingly claim, and desire to secure byLetters Patent, the following:

1. In a central energy telephone system, the combination with aplurality of lines extending to and connected with the instruments ofthe several subscribers served by a given exchange line, of aninterposed electro-magnetic switching appliance wherein said lines arecentered, line conductors ex'tending'therefrom to the exchange orcentral office, an actuating battery, and central ofiice apparatus" foractuating the switching appliance to connect any subscriber in circuitor all 01? the subscribers in common, and for connecting the line withother subscribers to the exchange, substantially as set forth.

2. In a central energy telephone exchange system, the combination with aparty-line switching appliance, of a plurality of party-line stationsconnected therewith and adapted to be alternatively connected orconnected in common with the exchange, associated telephone exchangeapparatus, line conductors extending to the telephone exchange, anactuating battery thereat adapted to energize the switching appliance, akey controlling the same, and

a signal controlled by said appliance forindicatingthe party connectedin circuit and the restoration of the aptact-making part, anelectro-magnetic device for effectingits rotation, and an additionalcontact controlled by the contact-making part adapted to he closed eachtime one of the party-line contacts is closed, and a signal at thecentral office adapted to'be actuated thereby, substantially assetforth.

4. In a telephone exchange system, the combination with a party lineswitching appliance, of means provided in the cord circuit for sendingactuating current over both line conductors in parallel to'saidswitching appliance, relay apparatus for sending current over one side,of the'line thereto, and means controlled by the removal'of theconnecting plug for restoring said relay apparatus to normal condition,substantially as set forth.

5. In a party-line, switching appliance, the combination with .aplurality of contact parts respectively connected with the severalparty-line stations, of a rotatable contactmaking part, anelectro-magnetic device for effecting its rotation adapted to beconnected with the exchange line conductors, said line conductorsextending to an exchange, and an additional contact'controlled by therotatable contact-making part adapted to be closed .each time one of theparty-line contacts is closed, substantially as set forth.

6. In a party-line switching appliance, thecombination with a rotatablepart, of electro-magnetic actuating apparatus therefor, contact-makingshoes mounted upon said part, a plurality of contacts adapted to beconnected with corresponding party-line stations, a signal-controllingcontact, relay-controlling contacts, said contacts being (llsposed'inthe path of, and adapted to be engaged by said shoes, and relayapparatus, substantially as set forth.

7. In a telephone exchange system, the combination with a junction-boxcontaining selective switching apparatus, of a central station aplurality of party-line stations, line and extension conductors.connecting said junction'box with all of said stations, electro-magnetlcactuating apparatus for effecting the selective switching andrestoration of said junction-box, the same being connected with one sideof the line, relay apparatus 1/ and -z connected in bridge to ground,relay w associated therewith, a source of current at the centralstation, and controlling switching appliances for cfiecting theselective and restorative opera' tions of the junction-box apparatus,substantially as set forth. 1

8. The combination with a telephone line having a plurality ofsubstations connected thereto, of a signal-bell connected with the line,a condenser inseries therewith 9. In a party-line selective switchingmechanism, the

combination with a movable controlling part, of electromagneticactuating mechanism therefor adapted to be electricaliy controlled;contact terminals controlled by the" movement of said part adapted to beconnected by individual circuits with a plurality of telephonesub-stations, and means for automatlcallychecking the said controllingpart in definite contact controlling positions substantially as setforth.

.10. The combination with the two limbs of a telephone exchange line, ofa plurality of telephone sub-stations associated therewith, a switch ateach sub-station adapted to control the flow of current across saidlimbs, an electromagnetically actuated switching mechanism interposedbetween the-exchange and said sub-stations adapted to selectivelyconnect to line any one of the sub-stations or connect all in multiple,and also control the flow ofcurrent across the limbs, and a switchcontrolled thereby connected between the exchange and theelectromagnetic switching mechanism, substantially as set forth'.

11. The combination with a multiple station telephone line, of a relayconnected with the line adapted to be excited by current flowingtherein, a line signal controlled by the relay, an electromagneticswitching mechanism connected between the terminal Jack of the line andits substations, said switching mechanism comprising means for normallymaintaining a closed circuit to all of the substations in multiple,whereby anystation may actuate the line signal, and also means undercontrol of the exchange operator for breaking this common circuit andestablishing an individual circuit to any one of the sub-stations,substantially as set forth.

. 12. In a' selective party line system, the combination with the cordcircuit at the telephone exchange, of a source of current, a key adaptedto open the cord circuit and send current in parallel over the limbs ofa connected telephone line, and relay apparatus comprising amultiple-contact device connected in circuit to complete, when excited,the cord circuit of the side in use, open the Opposite side, com plete acircuit from the source of current to one strand oi! the cord circuit,and close a secondary supervisory signallug circuit, substantiallyas setforth.

13. In a party-line switching mechanism, the comhination with .arotatable contact-controlling part, of electromagnetic means forrotating the same, sub-stationand signaling circuit contacts or,terminals associated with said part and controlled by its movement, anda signal at the central-oflice or exchange electrically connectedtherewith,

whereby any one of several sub-station lines may be exclusivelyconnected with the main line and the signal at the exchange. may beactuated each time one of said lines is thus connected, substantially asset forth.

14. The combination with a telephone line extending to a central stationor exchange, of a plurality of sub-stations normally connected with theline, an automatic electromagnetically actuated switching applianceinterposed in the said line between the exchange and said sub-stations,whereby the normal circuit to the sub-stations may be broken and anindividual circuit to any one of said substations may alternatively becl0sed, and means provided at the exchange for actuating said switchingappliance, substantially as set forth.

15. The combination with a telephone exchange, of a multiple stationtelephone line extending therefrom affording a metallic talking circuit,a plurality of sub-stations normally connected thereto upon individualcircuits, :1 third conductor uniting the exchange and the sub-stations,and an eiectro-magnetic switching mechanism bridged between one o'f theline conductors and the third conductor, said switching mechanism beingconnected to control the individual circuits and adapted to selectivelyconnect alter- 16. The combination with a multiple station telephoneexchange line, of a relay associated therewith at the exchange adaptedto respond to current flowing over the line, a signal controlled by therelay an electrically actuated switching appliance interposed betweenthe telephone stations and the exchange, and means at the exchange foractuating the switching appliance; said appliance being adapted to beoperated to close under predetermined conditions, a low resistancebridge across the line and thus actuate said signal, whereby theoperator is informed of 10 the condition of the switching appliance,substantially as set forth.

Signed at Detroit, Michigan, this 24th day of January 1902.

ARTHUR J. FARMER.

Witnesses:

S. E. 'lnuuas, CHARLES h. ADAMS.

